The present invention relates to a sports shoe.
Currently, in the manufacture of sports shoes, such as for example roller skates, ice skates, ski boots or snowboard boots and trekking boots, the technical problem is strongly felt of simultaneously achieving two contrasting properties: a high structural rigidity for optimum force transmission and a high comfort for the foot during the sport practice.
French patent No. 1,395,865 discloses an improvement to sports shoes, particularly ski boots and skating boots, wherein a stiffening element is inserted inside a shoe and is substantially constituted by a rod having an L-shaped cross-section and arranged at the rear end of the shoe. The lower end of the stiffening element is inserted in the heel of the shoe, while the upper end is substantially C-shaped so as to surround the calf proximate to the upper end of the shoe.
This shoe does not solve the above-cited problems, because the rod does not ensure continuous and gradual support of the entire foot being active only during backward movements of the ankle. Moreover, the rod does not offer optimum lateral support, because it is subjected to torsion under said load.
U.S. Pat. No. 3,747,235 discloses a ski boot having a substantially L-shaped lever element which is rigidly connected, in a downward region, to the sole and extends upward up to the calf region.
This shoe offers a rear support to the leg of the user but does not also offer an equal support for the entire foot. Moreover, as in the previous shoe, optimum lateral support is not provided, because the lever element is subjected to torsion in case of lateral forces applied hereto.
These drawbacks are also observed in the other conventional shoes, with the further drawback due to the presence of means interposed between two mutually articulated components in order to limit mutual forward or backward flexing.
AT-337,047 discloses a ski boot having a substantially L-shaped internal stiffening element which is embedded directly in the structure that composes, in the illustrated case, a boot.
Also this shoe entails the above drawbacks, although the stiffening element has a longer wing which also affects the plantar arch region of the foot.
French patent No. 74 01671 discloses a ski boot constituted by a monolithic shell comprising an upper which is rigidly coupled to a sole and a rear quarter which has, in its upper part, two supports which surround the leg, the quarter being articulated to the shell by means of a stud.
However, a rigid structure is obtained which is suitable only for some sports activities and thus does not solve the technical problem mentioned initially.
Italian patent No. 1,051,302 discloses a boot composed of two bodies which are generally L-shaped in a lateral view and mutually overlap along lateral joining lines. The bodies are kept in this active position by fixing means.
The two bodies have stiffening ridges in preset regions and underlying walls which connect the ridges. Therefore, the two bodies must have at least two edges for joining and closing the two parts, in order to ensure securing of the foot and tightness against water infiltrations.
Accordingly, the regions proximate to the joint must be rigid and nondeformable in order to avoid compromising their tightness. This fact, however, entails a considerable limitation in the obtainable forward flexing of the leg, due to their advanced position.
Said regions further prevent, if they are rigid and nondeformable, any lateral flexing of the ankle if this is required by the particular type of sport being practiced.
The stiffening ridges also cover the entire outer surface and extend to the front regions, where they can limit the forward flexing of the leg, at the same time forming pressure points on the foot and on the leg and limiting the comfort of the boot during use.
Italian patent application No. 41654 A/82 relates to a method for manufacturing sports shoes which are substantially constituted by a shoe which does not have a sole and is inserted at a rigid shell that affects the sole of the foot, the sides of the foot, and part of the toe region and wraps to the rear around the heel alone.
The resulting shoe still does not solve the described technical problems, because it does not allow adequate stiffening and foot support, for example for skiing or skating. Moreover, due to the presence of the shell that surrounds the tip of the foot, problems may arise in terms of the flexing of said foot.
In any case, this shoe allows neither optimum transmissions of lateral forces nor optimum lateral support. Additionally, if the shell affects part of the user's leg, it requires the preliminary provision of openings and/or slits in several points to allow an easy foot insertion, once again negatively affecting both the lateral tightness and the flexibility of the shoe.
EP-0 484 845 discloses a ski boot composed of a shell and a cuff which are rigid and associated with flaps, mostly made of a soft material such as leather, fabric or other.
In the lateral regions of the cuff there are provided two stiffening elements suitable to transmit the forces from the leg to the boot.
Both stiffening elements are rotatably coupled to the shell, approximately at the malleolar region, by means of suitable studs.
Also this shoe entails drawbacks due to the constructive complexity of the shell and of the cuff, which are made of different materials. Subsequent assembly by means of studs is a further constructive complication which increases the final cost of the product.
EP-0 582 551 discloses a ski boot made of plastics, in which a shell is provided to which a rear quarter is articulated. At the quarter and shell there is provided a stiffening element which is connected approximately at the heel region and is composed of a first lower body connected at one end to a second body which surrounds the upper/rear part of the boot.
Also this solution entails the drawbacks of the cited prior art and therefore does not solve the mentioned technical problem.